Stochastic Resonance in a Time-Delayed Mono-Stable System with Multiplicative and Additive Noise

The stochastic resonance （SR） in a time-delayed mono-stable system driven by multiplicative white noise, additive white noise, additive dichotomous noise as well as a periodic square-wave signal is considered from the view of the signal-to-noise ratio （SNR）. It is found that the SNR increases monotonically with the increase of the delay time. The SNR exhibits the SR behavior when it is plotted as a function of intensities of the noises, displaying the asymmetry of the dichotomous noise. The SNR varies non-monotonically with the increase of the system parameter and the amplitude of the input square-wave signal.     

污垢热阻恒定应力加速寿命试验研究

为缩短渐近污垢试验时间,本文定义了污垢寿命,利用恒定应力加速寿命试验(简称恒加试验),基于定数截尾 指数寿命统计分析方法,求得加速系数a, b近似最小二乘估计,然后由加速模型求得在正常应力水平下的平均寿命估 计。实例计算结果表明,对渐近型污垢热阻进行加速试验是可信的,也是可行的。这对污垢试验研究具有重要价值。     

Stochastic Resonance in an Over-Damped Bias Linear System with Dichotomous Noise

The stochastic resonance in an over-damped bias linear system subject to multiplicative and additive dichotomous noise （DN） is investigated. By using the linear-response theory and the properties of the DN, the exact expressions are found for the signal-to-noise ratio （SNR）. It is shown that the SNR is a non-monotonic function of the correlation time of the additive DN, and it varies non-monotonically with the bias of the external field, the intensity and asymmetry of the multiplicative DN, as well as the external field frequency. Moreover, the SNR depends on the bias of the system, as well as the strength and asymmetry of the additive DN.     

气相色谱-质谱联用法测定槐花中挥发性化学成分

槐花样品经蒸气蒸馏及乙醚萃取处理所得挥发油,用气相色谱-质谱联用法进行分析,按峰面积归一化法求出挥发性化学成分的相对含量.分离出42个峰,已鉴定了26个化合物,占其挥发油总相对含量的87.76%.已鉴定的有酸、酯、烯烃、醇、烷烃等10类化合物.其中酸类化合物占总色谱流出峰面积的30.53%,酯类占19.26%,烯烃类占18.01%,醇类占8.64%,烷烃类占5.52%.其主要组分有n-十六酸(26.43%)、17-三十五(烷)烯(14.84%)、喇叭茶萜醇(8.00%)、十六酸甲酯(4.18%)、肉豆蔻酸(4.10%)、8,11-十八碳二烯酸甲酯(3.79%)、月桂酸酐(3.60%)、9-十八(碳)炔酸甲酯(3.26%)、1,2-邻苯二甲酸丁基环己基酯(3.03%)、c-榄香烯(2.66%).     

复合钙硅固硫剂的固硫反应动力学研究

用机械混合法、沉淀法及溶胶-凝胶法制备了Ca-Si系列复合固硫剂,并用热分析法分别研究其固硫性能和固硫过程,用等效粒子模型对固硫反应的动力学过程进行表征,计算了各固硫反应的动力学参数.研究结果表明,氧化钙固硫动力学参数活化能与指前因子之间存在着耦合现象,即反应活化能Ea下降时,指前因子k0相应下降,反之,活化能增加时,指前因子相应增加.用不同方法制备的Ca-Si复合固硫剂的固硫性能和固硫过程有明显差别,但其固硫率都高于纯CaCO3,其中溶胶-凝胶法效果最好;Ca-Si系列复合固硫剂对固硫反应的影响表现为在反应初期(即化学反应控制阶段),其反应速率较纯CaCO3的低;而到反应后期(即产物层扩散控制阶段),其反应速率显著增加,固硫反应温度越高,这种影响越明显,与固硫转化率的实验结果非常吻合.     

铈、钇在AZ91D镁合金中的存在形式及其作用

在AZ91D镁合金中添加稀土元素Ce和Y,研究了Ce,Y元素在铸态AZ91D镁合金中的存在形式以及对合金组织和性能的影响。结果表明,铸态AZ91D镁合金中加入的Ce,Y大部分形成Al4Ce和Al2Y化合物,少量剩余的Ce,Y部分取代Mg元素的位置,以代位固溶的形式固溶在α-Mg固溶体和β-Mg17Al12金属间化合物中;Ce,Y能够细化镁合金铸态组织的晶粒,使Mg17Al12相发生"断网"并减少其在组织中的相对比例;适量添加Ce,Y能够提高AZ91D镁合金铸态机械性能,其主要原因是Ce,Y的细晶作用、固溶强化作用、Al-RE相的第二相强化作用以及对Mg17Al12相强化作用的改善。     

A New Mn(Ⅱ) Coordination Polymer with a Rare Polyrataxane Topology: Synthesis,Crystal Structure and Luminescent Property

A novel coordination polymer [Mn(bcp)(bib)0.5]n(1, H2 bcp = 1,3-bis(4-carboxyphenoxy)propane and bib = 1,4-bis(imidazol-1-yl)benzene) was synthesized under hydrothermal conditions, and was characterized by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy and powder X-ray diffraction(PXRD).Complex [Mn(bcp)(bib)0.5]n(1) is of triclinic system, space group P1 with a = 7.320(5), b =11.871(5), c = 13.932(5) ?, α = 111.125(5)°, β = 99.658(5)°, γ = 101.104(5)°, Z = 2, V= 1070.3(9)?3 Mr = 474.34, Dc = 1.472 g/cm3, F(000) = 488, μ = 0.660 mm?1, the final R = 0.0353 and wR =0.0.984 for 4373 observed reflections with I 2?(I). Structure analysis reveals that complex 1 displays a rare 2 D + 2 D → 2 D polyrataxane topology. Moreover, the luminescent property for 1 was investigated at room temperature.     

HPLC法测定大鼠盲肠内容物中5-氨基水杨酸的含量

建立高效液相色谱法测定5-氨基水杨酸在大鼠盲肠内容物中的含量.色谱柱为依利特C18柱（Hypersil BDS,200mm×4.6mm,5μm）,流动相为磷酸盐缓冲液（含0.01mol·L^-1四丁基溴化铵,pH 6.6）∶甲醇=75∶25 （V/V）,流速1.0mL·min-1,检测波长240nm.实验结果表明大鼠盲肠内容物中的内源性物质不干扰测定;线性范围为1.0-64.0μg·mL^-1（r=0.9994）;样品日内日间精密度的RSD均小于2％,回收率在99％-101％之间.本法快捷、灵敏、准确,可用于5-氨基水杨酸大鼠盲肠内容物药物浓度的测定.     

PVC-丁二酮肟膜修饰玻碳电极及其在钯的分析中的应用

制备了 PVC-丁二酮肟修饰电极 ,研究了膜电极的响应过程和钯在此电极表面的伏安特性。用微分脉冲伏安法测定 ,钯在 4.76× 1 0 -9mol/ L～ 9.53×1 0 -8mol/ L 的浓度范围内 ,电流与浓度的对数成线性关系 ,检出限为 1 .52×1 0 -9mol/ L。此法可用于矿样中钯的测定。     

Stochastic resonance in a bias linear system with multiplicative and additive noise

In this paper, the stochastic resonance in a bias linear system subjected multiplicative and additive dichotomous noise is investigated. Using the linear-response theory and the properties of the dichotomous noise, this paper finds the exact expressions for the first two moments and the signal-to-noise ratio （SNR）. It is shown that the SNR is a non-monotonic function of the correlation time of the multiplicative and additive noise, and it varies non-monotonously with the intensity and asymmetry of the multiplicative noise as well as the external field frequency. Moreover, the SNR depends on the system bias, the intensity of the cross noise between the multiplicative and additive noise, and the strength and asymmetry of the additive noise.